Sparking plug



July 3, 1928.

G. MICKEL.

SPARKING PLUG Filed July 18, 1927 Patented `uly 3, 1928.

PATENT oFFic GEORG MICKEL, F LOBAU, GERMANY.

' SPARKING PLUG."

Application led July 1B, 1927, Serial No.

This invention relates to sparking lugs for internal combustion engines of any d.

It has become known to provide in sparking plugs Ventilating holes to prevent exces- 5 sive heating. These air orl Ventilating holes are not sutlicient for cooling, owing to the high temperatures of the actually used engines. Excessive heating occurs consequently which causes defects of the insulator l0 and of the electrodes so that the sparking plug becomes untit for use.

These inconveniences are obviated by the present invention.

According to the inventionthe insulator has in its middle thickened portion'a circular groove by which an air chamber is formed which extends around the insulator. This air-chamber communicates with the atmosphere through openings in the sparking plug body, suitable devices being arranved'to regulate said openings so that they migllit be closed partly or completely.

`Another characteristic feature ofthe invention is that' the metal sleeve which encloses the lower portion of the insulator extends from the point of the insulator into said nir-chamber. i

A n embodiment of the invention is illustrated, by way'of example, in the accompanying drawing, in which Fig. l is a longitudinal section.

Fig. 2 shows in elevation the complete sparking plug with fully opened regulating envelope.

The middle portion of the insulator a, which is of greater diameter than the other parts of the same, has a circular groove d of. curved cross section. Owing to this groove the insulator is separated into an 40 upper conical portion b and a lower conical portion c. The groove forms an air chamber d which extends around the insulator. The lower port-ion of the insulator is covered by a tightly fitting metal sleeve e of copper, aluminum or the like. This metal sleeve. e extends from the point of the insulator u to the air-chamber al. This metal sleeve c 1s situated between the insulator a and the sparking plug casing and it ensures a reliable packing 'of the insulator, and as the packing surfaces are rather large neither air, oil or soot can penetrate through them 206,763, and in Germany October 19, 1928.

between the sparking plug casing and the insulator, the prejudicial flame contact with the insulator being absolutely prevented.

The metal sleeve e presents further the advantage lthat it deflects the heat from the lowermost portion of the insulator towards the air chamber d so that any accumulation of heat in the lower portion of the insulator is avoided. The metal sleeve forms, for instance, a heat transmitter and prevents self-ignition owing to the point of the insulator getting red hot and insulator defects. Openings g in the sparking plug casing f serve further for cooling the insulator. nir cooling is adjustable owing to an envelope It mounted on the sparking plug-casing so that it can be turned around the same. This regulating envelope l1. has apertures z', slits or holes, which correspond with the openings g in the sparking plug casing. The regulating envelope la, can be turned around the insulator casing without removing the sparking plug from the engine. The turning movement of the regulating envelope li is limited by a stoppin k. Owing to the regulatingenvelope 'and to the openings in the same and in the sparking lug casing, the cooling eii'ect can be regu ated in accordance with the conditions of temperature in the engine. To avoid accidentaldlsplacing of the regulating envelope h it is securely held by a split resilient ring m.

I claim cbpark plug with air cooling for internal comlmstio|i,engines, comprising in combination an insulator having a circular groove 1n its middle portion of greaterdiameter than the remainder and forming an air chamber around the insulator', a sparking plug body in which said insulator is located and having openings in the form of-slots, ametal sleeve tightly fitting over the lowermost portion of the insulator and extending up to said air chamber, and a metal sleeve mounted on said sparking plug casino so that it can turn around the same said regulating envelope having openings 1in-responding with said .openings in the sparking plug casing which can be closed partly or entirely.

In testimony whereof I allix my signature.

GEORG MICKEL.

This 

